With wide applications of the liquid crystal panel, there have been improvements in the development of liquid crystal panels. In order to improve display quality of the liquid crystal panel and decrease power consumption of a liquid crystal display, a conventional liquid crystal panel generally adopts a dot-inversion driving technology, which can improve the display quality of the liquid crystal panel but can increase power consumption of a source driver.
FIG. 1 is an equivalent circuit illustrating a part of a conventional liquid crystal panel. As shown in FIG. 1, the liquid crystal panel includes N×M pixel units (only 3×4 pixel units are shown in the Figure), where N is the number of columns of the pixel units and M is the number of rows of the pixel units. Each pixel unit 10 includes a gating line G1, a gating line G2, or a gating line G3 . . . , a data line D1, a data line D2, or a data line D3 . . . , a Thin Film Transistor 101, a storage capacitor 102 and a liquid crystal capacitor 103. A common line 11 is configured between the gating lines. One end of the storage capacitor 102 is a pixel electrode (not shown in the Figure); and the other end of the storage capacitor 102 is a storage electrode (not shown in the Figure). One end of the liquid crystal capacitor 103 is a pixel electrode (not shown in the Figure), and the other end of the liquid crystal capacitor 103 is a contraposition electrode (not shown in the Figure). The gate electrode of the Thin Film Transistor 101 (not shown in the Figure) is electrically connected with the gating line G2; the source electrode of the Thin Film Transistor 101 (not shown in the Figure) is electrically connected with data line D1; and the drain electrode of the Thin Film Transistor 101 (not shown in the Figure) is electrically connected with the pixel electrode (not shown in the Figure) through a through hole (not shown in the Figure).
In the liquid crystal panel shown in FIG. 1, the pixel units 10 with the same polarity in two adjacent columns are electrically connected with one data line. In one frame time, when gating pulses are inputted to different gating lines, i.e. different gating lines are scanned, the amplitude of a voltage applied to a single data line changes little because the pixel units electrically connected with the single data line have the same polarity, and thereby the power consumption of the source driver is decreased relatively.
FIG. 2 is a driving simulation chart of the conventional liquid crystal panel shown in FIG. 1. At the time of alternation between frames, a single data line provides each pixel unit 10 with a plurality of inverted data voltages. For example, in the nth frame, a data voltage higher than a common voltage Vcom is applied to the pixel electrode, and the pixel unit has a positive polarity represented as “+”. In the (n+1)th frame, a data voltage lower than the common voltage Vcom is applied to the pixel electrode, and the pixel unit has a negative polarity represented as “−”. When a gating pulse is applied to a corresponding gating line, the Thin Film Transistor 101 connected with the corresponding gating line is turned on, the data voltage is applied to the pixel electrode (not shown in the Figure), and the liquid crystal capacitor 103 and the storage capacitor 102 are charged. When the gating pulse applied to the corresponding gating line is off, the Thin Film Transistor 101 is disconnected with the corresponding gating line, and the pixel electrode (not shown in the Figure) keeps a voltage value after being charged until the Thin Film Transistor 101 is turned on again.
In the nth frame, the data voltage of 15 V is applied to the data line. After a scanning start signal is applied to a gating line and when the gating line is on a high level, the Thin Film Transistor connected with the gating line is turned on. Through the Thin Film Transistor, the liquid crystal capacitor of the pixel unit is charged with the data voltage of 15V on the data line, and the pixel voltage on the pixel electrode reaches a voltage value equal to the destination data voltage. However, at the moment that the scanning signal is off, a decreasing feed-through voltage ΔVp is generated for the pixel voltage. After the scanning signal is off, the gating line is on a low level, the Thin Film Transistor is disconnected from the gating line, and the pixel electrode keeps the pixel voltage at about 12.5V. The common voltage Vcom is a constant 5V, and the liquid crystal voltage between the two ends of the liquid crystal capacitor maintains a positive voltage of about 7.5V.
In the (n+1)th frame, after the scanning start signal is applied to the gating line and the gating line is on the high level, the Thin Film Transistor connected with the gating line is turned on. Through the Thin Film Transistor, the liquid crystal capacitor of the pixel unit is charged with the data voltage of 0V on the data line, and the pixel voltage on the pixel electrode reaches a voltage value equal to the destination data voltage. However, at the moment that the scanning signal is off, a decreasing feed-through voltage ΔVp is generated for the pixel voltage. After the scanning signal is off, the gating line is on a low level, the Thin Film Transistor is disconnected with the gating line, and the pixel electrode keeps the pixel voltage at about 2.5V. The common voltage Vcom is 5V, and the liquid crystal voltage between the two ends of the liquid crystal capacitor maintains a negative voltage of about 7.5V.
In the conventional driving circuit for the Liquid Crystal Display (LCD) apparatus with an In-Plane Switching (IPS) liquid crystal panel or a Fringe-Field Switching (FFS) liquid crystal panel, an invariable Direct Current (DC) voltage value is taken as the common voltage, data voltages with a positive or a negative polarity respectively are provided to the data line in different frames alternatively. The polarities and value of the liquid crystal voltage applied between the two ends of the liquid crystal capacitor in the pixel unit depend on the polarities and values of the data voltage as well as the value of the common voltage. In order to stabilize the liquid crystal voltage at a demanded value, a source driver with a higher output voltage difference must be used so as to apply a high voltage to the pixel unit 10. This, however, increases the power consumption of the source driver and increases the costs of use of the liquid crystal panel.